Inactivation of Cryptosporidium parvum Oocysts and Clostridium perfringens Spores by a Mixed-Oxidant Disinfectant and by Free Chlorine.

University of North Carolina, Chapel Hill 27599, USA.
Applied and Environmental Microbiology (Impact Factor: 3.95). 12/1997; 63(11):4625.
Source: PubMed

ABSTRACT Cryptosporidium parvum oocysts and Clostridium perfringens spores are very resistant to chlorine and other drinking-water disinfectants. Clostridium perfringens spores have been suggested as a surrogate indicator of disinfectant activity against Cryptosporidium parvum and other hardy pathogens in water. In this study, an alternative disinfection system consisting of an electrochemically produced mixed-oxidant solution (MIOX; LATA Inc.) was evaluated for inactivation of both Cryptosporidium parvum oocysts and Clostridium perfringens spores. The disinfection efficacy of the mixed-oxidant solution was compared to that of free chlorine on the basis of equal weight per volume concentrations of total oxidants. Batch inactivation experiments were done on purified oocysts and spores in buffered, oxidant demand-free water at pH 7 and 25°C by using a disinfectant dose of 5 mg/liter and contact times of up to 24 h. The mixed-oxidant solution was considerably mute effective than free chlorine in inactivating both microorganisms. A 5-mg/liter dose of mixed oxidants produced a >3-log10- unit (>99.9%) inactivation of Cryptosporidium parvum oocysts and Clostridium perfringens spores in 4 h. Free chlorine produced no measurable inactivation of Cryptosporidium parvum oocysts by 4 or 24 h, although Clostridium perfringens spores were inactivated by 1.4 log10 units after 4 h. The on- site generation of mixed oxidants may be a practical and cost-effective system of drinking water disinfection protecting against even the most resistant pathogens, including Cryptosporidium oocysts.

Download full-text


Available from: Mark Sobsey, Sep 01, 2015
  • Source
    • "dissolved Cl 2 , HOCl, and OCl − ), hydrogen peroxide (H 2 O 2 ), ozone (O 3 ), and other short-lived radicals (e.g. hydroxyl radicals; OH • ).[12] [13] [14] Dimensionally stable anodes, such as platinum (Pt), iridium dioxide (IrO 2 ), and ruthenium dioxide (RuO 2 ) with titanium (Ti) as an electrode substrate, have been widely applied to the electrochemical oxidation process for water treatment due to its versatile electrocatalytic properties and stability in terms of long service life.[15] [16] In drinking water treatment, the main purpose of electrolysis is the in situ production of disinfectants, such *Corresponding author. "
    [Show abstract] [Hide abstract]
    ABSTRACT: The aim of this study was to evaluate the formation of oxidants and by-products by using different electrode materials, such as Pt/Ti, RuO2/Ti, and IrO2/Ti, in the electrochemical process. The harmful by-products [Formula: see text] and [Formula: see text] were formed during the electrolysis of a Cl(-) electrolyte solution, as well as active chlorine, which is the most common water disinfectant. With regard to drinking water treatment, the most efficient electrode was defined as that leading to a higher formation of active chlorine and a lower formation of hazardous by-products. Overall, it was found that the Pt/Ti electrode should not be used for drinking water treatment applications, while the IrO2/Ti and RuO2/Ti electrodes are ideal for use.
    Environmental Technology 02/2015; 36(3):317-326. DOI:10.1080/09593330.2014.946098 · 1.20 Impact Factor
  • Source
    • "There is an increasing interest in the use of C. perfringens as an indicator for water pollution and for monitoring water quality after processing. Further, studies have been conducted to correlate the occurrence of C. perfringens and protozoan pathogens in environmental waters (Payment, 1999; Payment and Franco, 1993; Venczel et al., 1997). The European Directive on drinking water quality has included C. perfringens as one of the microbiological parameters to be determined in order to control the quality of water for human consumption (EU, 1998) using mCP agar as the reference method for detecting C. perfringens in drinking water. "
    [Show abstract] [Hide abstract]
    ABSTRACT: The European Directive on drinking water quality has included mCP agar as the reference method for recovering Clostridium perfringens from drinking waters. In the present study, three media (mCP, TSCF and CP Chromo Select Agar) were evaluated for recovery of C. perfringens in different surface water samples. Out of 139 water samples, using a membrane filtration technique, 131 samples (94.2%) were found to be presumptively positive for C. perfringens in at least one of the culture media. Green colored colonies on CP Chromo Select Agar (CCP agar) were counted as presumptive C. perfringens isolates. Out of 483 green colonies on CCP agar, 96.3% (465 strains, indole negative) were identified as C. perfringens, and 15 strains (3.1%) were indole positive and were identified as Clostridium sordellii, Clostridium bifermentans or Clostridium tetani. Only 3 strains (0.6%) gave false positive results and were identified as Clostridium fallax, Clostridium botulinum, and Clostridium tertium. Variance analysis of the data obtained shows statistically no significant differences in the counts obtained between media employed in this work. The mCP method is very onerous for routine screening and bacterial colonies could not be used for further biochemical testing. The colonies on CCP and TSCF were easy to count and subculture for confirmation tests. TSCF detects sulfite-reducing clostridia, including species other than C. perfringens, and in some cases excessive blackening of the agar frustrated counting of the colonies. If the contamination was too high, TSCF did not consistently produce black colonies and as a consequence, the colonies were white and gave false negative results. On the other hand, the identification of typical and atypical colonies isolated from all media demonstrated that CCP agar was the most useful medium for C. perfringens recovery in water samples.
    International journal of food microbiology 06/2013; DOI:10.1016/j.ijfoodmicro.2013.06.012 · 3.16 Impact Factor
  • Source
    • "In the electrolysis of water containing NaCl the largest fractions produced apart from free chlorine are chlorine dioxide, hydrogen peroxide and other short-lived oxidants [14]. With the so-called MIOX method, Venczel et al. [15] showed that the electrolytically produced mixture is more effective in terms of decontamination than free chlorine alone. Further advantages are its low cost, the possibility of producing it in situ, the broad spectrum of its anti-microbial activity and its low toxicity. "
    [Show abstract] [Hide abstract]
    ABSTRACT: Background: A frequent problem in dental units is the microbial contamination of water and biofilm formation in the water supply lines. After random identification of a bacterial contaminated dental unit (310 cfu/ml) in a practise with 3 dental units we implemented the present study to evaluate the efficacy of the PotoClean® technology, based on anodic oxidation. Method: The efficacy of a regular low concentrated permanent decontamination (1 mg Cl/L) with an additional intensive decontamination by PotoClean® (three times 20 mg Cl/ml for 2 h) on three dental units was tested over 7 months. Microbial contamination, total chlorine concentration and redox potential have been analyzed. Dental unit A and B was 15 years old, unit C 5 years. Results: After 3 intensive decontaminations, in dental unit A and B the number of bacteria and moulds could be reduced less than 7 d. Thereafter the bacteria counts increased again during the subsequent 7 month period and the amount of moulds was with some exceptions 300 cfu/ml, although PotoClean® was constantly added in the system (1 mg Cl/L). After further 7.5 month only with low concentrated permanent disinfection (1 mg Cl/L) both units were successful decontaminated. Dental unit C represented an object which was easier to decontaminate because of the advanced construction (prevention of water stagnation) and the shorter useful life. At the beginning of the decontamination it was no bacterial contamination, but moulds were contained (300 cfu/ml). Already after the first intensive decontamination, no further bacteria and moulds could be detected. Discussion: An important factor for the efficacy of PotoClean® was the age of the units and their construction. For a new generation of dental units PotoClean® was effective during the whole period of monitoring. For two old types of dental unit with massive biofilm development the successful decontamination needed more than 7 month. Conclusion: The PotoClean® technology has resulted in even old-type turbines with intensive biofilm formation to complete decontamination. In a recent turbine design already after the first intensive decontamination with PotoClean® and its continuous use (1 mg Cl/L) no more contamination by bacteria and moulds were detectable.
    04/2012; 7(1):Doc10. DOI:10.3205/dgkh000194
Show more